Architecture Patterns Master proven backend architecture patterns including Clean Architecture, Hexagonal Architecture, and Domain-Driven Design to build maintainable, testable, and scalable systems. Given: a service boundary or module to architect. Produces: layered structure with clear dependency rules, interface definitions, and test boundaries. When to Use This Skill - Designing new backend services or microservices from scratch - Refactoring monolithic applications where business logic is entangled with ORM models or HTTP concerns - Establishing bounded contexts before splitting a system…